A wide variety of child resistant closures have been suggested and a number are currently available on the market. All of those which are marketed in the United States, to be sold as child-resistant, must meet certain minimum standards of difficulty of opening by small children. Of course, it is also desirable that they be readily openable by an adult, and without the necessity of complicated instructions or the like.
Many such closures are of the two-piece, push-down type. That is to say that a first part serves as the closure for the bottle or container and a second part surrounding or overlying the closure is adapted to engage with the closure to effect both closing of the container by the closure and opening, by counterclockwise rotation of the closure. In all of these there is a clutching mechanism which facilitates interengagement of the closure and the second surrounding part to induce rotation of the closure.
Many such closure assemblies incorporate a spring-like or vertically deformable construction which maintains the second part in an up-position which, when pushed down, causes engagement of the clutch parts to permit opening and closing of the container. Typical of such devices are those illustrated by U.S. Pat. Nos. 3,692,199, 4,069,935, 2,964,207, 3,638,819 and 3,812,990.
Other of such closure assemblies rely upon inclined surfaces which interengage both in the screw-off mode, and U.S. Pat. Nos. 3,924,770, 3,946,890 and 4,241,840 typify such devices. All of those devices utilize second parts which cover the top of the closure.
Another device currently in use utilizes a second part which is a topless collar, and functions by lifting the collar upwardly to facilitate removal of the closure, and such a device is illustrated by U.S. Pat. No. 3,669,294.
Yet other devices utilize a squeeze-type of interaction between an overlying cap and a closure to permit unscrewing of the closure, and U.S. Pat. No. 3,809,274 typifies such a device.
All of these devices are made of at least two parts, frequently of diverse materials, which then require subsequent assembly. These devices, when assembled from multiple parts, require matching of parts to fulfill their childproof function.